Improvement in metallurgical furnaces and processes



2Sheets--Sheetl. N. W. WHEELER. Metallurgical Furnaces and Processes.

Palented Oct. 27,1874.

, THE GRAPHIC CQPHQT6-UTHB QL4-I PARK PLACE,B .Y.

2 Sheets- -Sheet 2'.

' 1N. w. wHE f|. ER. I MetaHurgica l'F-urnaces and Processes.N0.156-,244.

Patentd Oct. 27,1874.

I 'Srpu e am UNITED STATES PATENT OFFICE.

NORMAN w. WHEELER, on NEW YORK, ...Y;

IMPROVEMENT m METALLURGICAL FURNACES AND PROCESSES.

Specification forming part of Letters Patent No. 156,244, dated October27, 1874; application filed v April 23, 1874.

To all ,whom it may concern: 4

Be it known that I, NORMAN W. WHEELER, a resident of the city, county,and State of New York, have invented an Improvement in MetallurgicalFurnaces and Processes, of which the following is a specification:

This invention relates chiefly to a process for a reduction of metalsfrom the oxides there of, wherein the ore to be reduced is in the formof sand, and is showered down through a double atmosphere composed of acolumn of flame immediately over a column of carbonic oxide or otherreducing gas; and its objects are to provide for the production,regulation,

and management of the necessary shower of ore or ores and reagents forthe proper treatment of the product of the oreshower after itsfallthrough the aforesaid double atmosphere of flame and reducing-gas. u

The following is a description of what I consider the best means ofcarryingout the invention:

In the drawings forming a part of this specification, Figure 1 is an endelevation of an improved metallurgical furnace. Fig. 2 isa sectionalelevation of the same; and Figs. 3 and 4 sectional and half full plansand elevations of parts thereof upon an enlarged scale, showing morefully the details of construction.

port of auxiliary apparatus; and D I) and E- E are feeding apparatus forthe introduction and regulation of the ore, flux, and reagents. Thereducing-shaft A and balling furnace B, taken together, resemble, ingeneral appearance and construction, an ordinary puddlingfurnace andchimney fitted to work with gaseous fuel, a being the gas-conduitleading from a gas-producer or a gas-well; b, an air-inlet fitted withthe regulating-door i, and c the furnace or puddling door, below whichis seen the balling-hearth, separated from the gas-conduit by abridge-wall. This furnace differs, however, from the commonpuddlingfurnace in that there is fitted an extra door, 01, in thewall atthe chimney end, and a hearth immediately under the shaft A, so disposedthat a mass of matter having fallen down the shaft A may be convenientlypushed over into the balling-hearth from the shaft-hearth with tools putthrough the door (1.

Matters resting upon the balling-hearth may be treated by simpleheating, as in an ordinary reverberatory furnace, and the flame to whichthey are subjected may be made either reducing or oxidizing by theproper regulation of the inflowing gas and air through a and b, and theusual manipulation of balling or puddling may be ,made with tools putthrough the door o. At a considerable height above the hearthsay, forthe treatment of some ores, at half the height through which the ore isto fall-the sides of the reducing-shaft A are pierced with air-holes g gg of such area as to allow the entrance of enough air to burn thereducing-gases as they rise to the level of the full combustionair-holes g g y, when the doors 0, d, and b are closed, and but littleor no air enters the shaft or the furnace below the fullcombustion-holes g g g. The result of this arrangement of things is thereducing-gases coming in from the gas-producer, which may be of anysuitable sort, will pass through the furnace B and rise through theshaft A, taking up as it goes heat from the walls of the furnace andshaft if they have been previously heated by full combustion in thefurnace B. At the level of g g g, the rising gas column may be ignited,and the continual indraft of air will support full combustion, so thatthe part of the shaft A abovethe level of g g g will be filled with acolumn'of flame which will have great and instantaneous heating powerover particles of sand ore which may fall through it.

Assuming, for the present, that a stream of ore in the form of sand islet fall from each of the inclined feed-holes f f, and is directedtoward the middle of the shaft A by passing over the projections s s,and so scattered pretty e renly over the area of the shaft in a shower.The effect of the heat upon each particle will be to heat, and, perhaps,to fuse it before it shall have fallen to the level of g g g, and alsothe sudden exposure to heat will cause the larger particles to crack andbreak up into smaller particles by reason of differences in expansion,so that the particles composing the shower will fall out of the flameabove 9 g 9 into the reducing-gases below 9 g gin the best possiblecondition for the prompt action upon them of the reducing-gases, whichaction will result in the extraction of the oxygen while they arefalling through the reducing-gases to the hearth at thebottom of theshaft, and the reducing action will continue upon the successive layersof the resulting heap formed upon the shaft-hearth.

It is intended that the flame and reducing gases shall be enabled to actupon the ore with sufficient promptitude to accomplish reduction withinthe time occupied by its fall from ff to the hearth, and the time ofsubsequent exposure, by reason of the great surface exposed compared tothe mass, which is a result ofits granular form of sand, and the finerthe sand the greater will be the time occupied in falling through agiven distance, and the less will be the time required for itsreduction, so that the finer the sand to be operated upon the less maybe the height of the reducing-shaft A.

When treating iron ore this apparatus will be worked in this wise: Thefuel gases will flow in through the conduit a, and the door 1; will beopened to supply air for full combustion in the'oven B, and this will becontinued until the inner surfaces of the oven -B and lower parts ofthe. shaft A are heated to a white heat; then the door 2' will beclosed, and the gases be fired at the full combustion air-holes g g 9,thus establishing the conditions of reduction, and then the streams orshower'ofore from the feed-holes f f will be established and continueduntil a sufficient heap of reducedmetal or iron sponge shall haveaccumulated at the 4 foot of the shaft A. The shower of ore will then bestopped, the door d be opened, the sponge be quickly pushed over intothe ballinghearth, and the doordclosed, so as to expose the iron spongeto the oxidizing action of the air for as short a time as possible. Thedoor '0 will then be opened and the gases be fired in the oven B, andthe flame regulated to oxidize or carbonize the sponge upon the hearth,as may be required, and the sponge compacted into balls suitable forfurther working by squeezers or hammers in the usual way.

. If particles of ore strike and adhere to the sides of thereducing-shaft while reduction is going on, the adhering masses willbe-melted off during the next balling term, and only a thin glazing ofoxides be left upon the surfaces, which will not be objectionable.

There will be but little fluxing required if the ore be reasonably pure,and especially so.

if there be.a dust-chamber included in the conduit a, leading from thegas-producer, to arrest and retain silicious dust, which might otherwisebe carried along by the current of gases. This apparatus difi'ersessentially from those in which operations are carried on by solid fuelburned in contact with the ore and in which the earths of the fuel, aswell as those of the ore, have to be fluxed to be got rid of. So muchfluxing material as may be required should be reduced to sand or powder,and mixed with the ore in definite proportions previous to itsintroduction into the furnace, as has been done in many singleatmospherefurna'cesnotably in Mouchells furnace-or, for the sake of amore sure'and even difi'usion of the flux with the ore, the flux shouldbeintroduced, say at 6, into the reducing-shaft by means of a feedingdevice similar to that used for the introduction and regulation of theore, the ore and the flux-feeding machinery being connected together tofeed proportionately, and at the sametime so that the flux will'bemingled with the ore as it falls through the shaft in a shower.

Whenever it is desirable that the fluxing powder be exposed to theaction of the flamecolumn, the flux-feed holes e and accompanyin gfeeding apparatus should be removed from the positions in which they areshown, and attached to the reducing-shaft A above the level of g g g. Itwill be convenient to make such attachments above the level of thefeedholes f f, for the reason that an extra admission of air above thatlevel will do no harm, whereas if the attachment be made with the heightof the reducing-column, the flux-feeding apparatus must be made so as toexclude air, otherwise some. of the-reducing-gas would be burned atthelevel of the flux-feed holes. I A form of feeding apparatus isshown'in Figs. 3 and 4. At each of the feed -holes ff is attached,to.the reducing-shaft A, a hopper, n,'with a partly-open top. To theframe-work is attached another hopper, l,

with a narrow opening 0, at the bottom, to deliver into the opening inthe top of n, at

1, which openingris so large as to permit the insertion of a-bar intothe, feed-hole to clear away any obstruction which may form, f and alsolarge enough to permit a stream of 7 air to be drawn through thefeed-holes ff, and across. the open mouth 0, so that, if ore be fallingfrom 0, the current of air will tend to break up any loosely-compactedlumps as they fall through it.

The current of air mentioned will exist by reason of the height of theshaft A above the feed-holes ff, which is for the primary purposeofcarrying the products of combustion above the uppermost platform ofthe framework. These currents of air may be increased by the attachmentof a fan-blower, should such increase be necessary. The feed-holes f fare placed opposite each other, in order that such a way that any twocontiguous wings and the projecting heads will form a trough. Overthefeed-cylinder m is mounted the hopper k,into which the sand isto be putin mass. The outlet of 7c is a narrow nozzle, t, somewhat shorter thanthe feed-cylinder m, and placed over and near the wings, so that, whenthe cylinder m is at rest, the ore will pass through the nozzle 17, andfill the uppermost troughs, but will not pass beyond the periphery ofthe cylinder m, because the natural angle of rest of the sand will makethe surfaces of the heap fall below the upper edges of one or another ofthe wings upon each side. If the cylinder at be revolved, eachtroughwill be filled as it passes under the nozzle t, and afterward spill itscontents into the hopper 1, whence it willpass by force of gravity intothe reducing-shaft A. If both cylinders be revolved at equal speeds,equal feeds will occur at each side of the shaft A. These cylindersare-to be connected with each other and with a steam-engine or othermotive power by means of suitable mechanismpulleys and belts or chains,for instanceso that the rate of feed may be governed by the speed of theprime mover, andchanged relatively thereto by well-known means.

The flux-feeding apparatus will be of the same character, and beoperated in the same way, the required quantity of flux relatively tothat of the ore being regulated by either different dimensions or bydifferent speeds.

The shield h surrounds the reducing-shaft A at the level of the fullcombustion air-holes g g 'g, to prevent the air from blowing directlyinto any of the air-holes g g g, and making the action irregular. Thesame object can be attained by inclosing a part or the whole of theframe-work C O. r

Apparatus for the reduction of metals with gaseous fuel has beenconstructed, whereby the ore was exposed by charges, and by largesurfaces, first to the heating action of a full combustion-flame, and,after the charge had become fused or sufficiently heated, the flame wassuppressed, and a stream of hot carbonic-oxide gas was directed upon thecharge. The necessary surface of exposure was obtained by a sort oftumbling action in a revolving oven, and the result is said to beexcellent. According to deductions from known facts, metals which arenot reducible, per 86, by simple exposure to the heat of a neutral flameshould be reduced by this intermittent process at a cheaper rate thanbythe common processes, involving exposure to only the heat and chemicalaction of a carbonic-oxide flame, or of a flame largely composed ofcarbonic oxide, for,

by utilizingonly the heat resulting from combustion to carbonic oxide,the potential heat of combustion from carbonic'oxide to carbonic acid iswasted; and such waste of potential heat must occur in all processeswherein both heating and reduction by carbonization is effectedor soughtto be effected by exposure to any single atmosphere or flame, whetherthe exposure be by shower, by mixture with solid fuel, by heaps uponhearths, or by charges in a tumblingfurnace, and'this waste will bear adirect relation to the quantity of carbonic oxidewhich escapes.

Taking the above-indicated tumbling fur nace as the best or mosteconomical, per se, heretofore known, and contrasting it with theapparatus now'under consideration, we see that, although the tumbling-furnace utilizes the heat of full combustion during the term of heatingthe ore, it necessarily wastes the po tential heat of so much carbonicoxide as escapes during the term of reduction, and much must be allowedto escape for the reason that the fact of reduction dilutes thereducing-gas by formation of carbonic acid, and largely-diluted.reducing-gases are not sufficiently effective;

whereas in the new apparatus, although the reducing-gases arediluted,the residueis constant ly burned at the air-holes g g g to formthe flamecolumn. Even when a carbonizing-flame is used in balling,theresidue of carbonic oxide is burned at g g g, and much of the resultantheat absorbed by the walls of the reducingshaft A, to be afterwardutilized in exalting the heat of the regular flamecolumn. so that at notime will the carbonic oxide go wholly to waste.

In treating ores of precious and other metals which are reducible, per80, by exposure to simple heat, and do not absolutely require 1 such apreponderance of affinity for oxygen as results from exposure toreducinggases, this apparatus is useful, in that simple heat may bereplaced to agreat extent by direct aifinity, and less fuel be used thanhas before been necessary.

When using this apparatus for the reduc tion of iron ores, eithercarburized cast-iron, steel, or neutral iron free from carbon may beproduced by the proper regulation of the vol-- ume, richness, and heightof the column of reducing gases. Neutral iron will be more easily andsurely produced than uniformlycarburized iron, for the reason that ifthe gases andheat be so regulated as not to reduce all of the originaloxide, but so as to leave a small part of it in the mass, to be fused orkept fused during the balling term, such fused oxide will work out ofthe balls in the form of slag, when under the hammer, and a considerablevariation in the conditions of reduction will result in a varia tion inthe quantity of slag produced rather than in a variation in the qualityof the iron.

In actual practice a considerable amount of such slag 1s desirable,because much impurity is carried out of the ball with it when the ballis hammered or squeezed.

If at any time the iron sponge at the foot of shaft A is found to beover-carburized, the mishap can be remedied by having the hearth linedwith oxide of iron fettlin g and the puddlings of the mass in theordinary way.

It is not essential that each particle of iron ore is reduced to ahomogeneous neutral state during its fall through the reducingshaft. Thelarger particles will be under-carburized, and each contain a nucleus ofoxide, with an outer shell of carburized iron, and an inner shell ofneutral iron, while the smaller particles will be completely carburized;but the general average will be equal to neutral iron, with an excess ofoxidized or carburized iron, as the case may be, and the intimatemixture of the particles and heat to which they are exposed will favorthe even diffusion of the carbon throughout the mass of reduced iron.

The preferable method of making steel with this apparatus is, to showerthe ore down through the double atmosphere, and receive it in a bath offused carburized iron upon the hearth, which should be extended for thispurpose all across the bottoms of the shaft and oven B to the bridgewall. The metal bath may be fused and kept fused by the occasionalfiring of the gases in the oven B, as for balling.

After the bath has been first made of carbu rized iron, the formalrenewal of it will be unnecessary so long as the apparatus continues inaction, because we have the means within the apparatus of so regulatingthe carburization of the sponge that a continuous bath may be maintainedupon the hearth by tapping off a part only of its contents at any time.

If at any time the bath is shown by samples, 'cooled and tested, to bedeficient in carbon the shower of ore may be decreased, or the volumeand speed of reducing gas may be increased, so as to make up thedeficiency, and vice .versa, if the bath is too highly carburized.

The great affinity which chromium exhibits for iron renders it easy tomake chrome steel directly from the ore with this apparatus.

It is well known that neutral iron melted in a crucible, along withchrome oxide, produces chrome-steel, and that the union of chrome withiron is more persistent or stronger than the union of iron with carbon;hence it is possible and easy to mix together in definite proportionsthe iron and chrome ores, and shower them down the reducing-shaftcontaining a double atmosphere of flame and reducinggases, and receivethe product in a bath of molten iron, carbonized or chromized in themanner hereinbefore described.

By reason of the preponderance of affinity before noted the shower ofiron may be under-carburized, and a residue of iron oxide left in themass by way of slag, so as not only to get the benefit of expellingimpurities with the slag, but to prevent the mixture of carburized ironwith the chromized iron; and it will be well when the reducing processis intermitted, and the gases fired in the oven B, for the purpose ofmaintaining the heat of the bath, to make the heating-flame stronglyoxidizing, so as to extract from the surface of the bath any carbonwhich may have been absorbed from the reducing-gases during the previousterm of reduction. The carburization of the bath may be mitigated orprevented by the vitreous slag, which will result from the use of fluxwith the ore. The chrome oxide may be mixed with the flux in differentproportions, and so introduced in relative quantities to those of theore.

This apparatus differs from all previous shaft-furnaces, in that theshaft A has its walls pierced by the full combustion air-holes g g g, ata height above the hearth sufficient to secure the reduction of thepreheated granulated ore during the time required for its fall. throughthe reducing-gas column, extending from the hearth to the level of theholes 9 g g, and also the walls are pierced by the feedingholes ff, atan additional height, sufficient to secure the requisite pre-heatin g ofthe granulated ore, during the time required for its fall through thefull combustion flame of residual reducing-gas, from the feeding-holesff to the holes 9 g g; and to describe this shaft, includin g the abnvementioned peculiarities, the words reducing-shaft are hereinafter used.

I claim- 1. The feeding apparatus D or E, consisting of the combinationof the chambered cylinder m, and hopper at, Z, and 70, substantially asand for the purposes described.

2. The combination of the feeding apparatus D'or E, with thereducing-shaft A, substantially as and for the purposes described.

3. The combination of the ore-feeding apparatus D, with theflux-feedingapparatus E, and the reducing-shaft A, substantially as andfor the purposes described.

4. The reducing-shaft A, having the full combustion air-holes g g g andfeed-holes ff, substantially as and for thepurposes described.

5. The reducing-shaft A, having full combustionholes g g g andfeeding-holes f f, and separate flux-holes e, substantially as and forthe purposes described.

6. The combination of the reducing-shaft A, with the reverberatoryfurnace B, air-conduit I), door 2', and gas-conduit a, substantially asand for the purposes described.

7. The process of treating crude metal reduced from the ore during itsfall through a column of flame over a column of reducinggas, bytransferring it from the foot of the reducing-shaft A to the hearthofthe reverbera tory furnace B, and therein exposing it to the action ofthe flame, produced and controlled substantially in the manner and forthe purposes described.

8. The process herein described of making carbon steelthat is to say, byshowering granulated iron ore down through a double atmosphere,consisting of flame over reducinggas, into a bath of carbonized ironmaintained in a state of fusion, substantially as and for the purposesdescribed.

9. The process herein described of making chrome steel-that is to say,by showering the ores of chromium and iron in measured relativequantities down through a double atmosphere, consisting of flame overreducinggas, and receiving the product upon a hearth or in a bath ofmolten metal substantially as and for the purposes described.

NORMAN W. WHEELER.

' Witnesses:

ARNOLD HiiRMANN, WM. 0. DEY.

